US4286087A - Chitin powder and process for making it - Google Patents
Chitin powder and process for making it Download PDFInfo
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- US4286087A US4286087A US06/077,831 US7783179A US4286087A US 4286087 A US4286087 A US 4286087A US 7783179 A US7783179 A US 7783179A US 4286087 A US4286087 A US 4286087A
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- chitin
- phosphoric acid
- dispersion
- mixture
- powder
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- 229920002101 Chitin Polymers 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000000843 powder Substances 0.000 title claims abstract description 20
- 230000008569 process Effects 0.000 title claims abstract description 17
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000006185 dispersion Substances 0.000 claims abstract description 15
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 9
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 claims abstract description 6
- 238000000227 grinding Methods 0.000 claims abstract description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 13
- 229910003944 H3 PO4 Inorganic materials 0.000 claims description 9
- 238000009835 boiling Methods 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 5
- 238000004108 freeze drying Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 238000010008 shearing Methods 0.000 abstract description 13
- 239000007788 liquid Substances 0.000 abstract description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 12
- 230000003287 optical effect Effects 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000000047 product Substances 0.000 description 7
- 238000011282 treatment Methods 0.000 description 7
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 5
- 239000011574 phosphorus Substances 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 125000002777 acetyl group Chemical group [H]C([H])([H])C(*)=O 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- 230000003301 hydrolyzing effect Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 241000238557 Decapoda Species 0.000 description 3
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 3
- OVRNDRQMDRJTHS-FMDGEEDCSA-N N-acetyl-beta-D-glucosamine Chemical compound CC(=O)N[C@H]1[C@H](O)O[C@H](CO)[C@@H](O)[C@@H]1O OVRNDRQMDRJTHS-FMDGEEDCSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229950006780 n-acetylglucosamine Drugs 0.000 description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 241000238097 Callinectes sapidus Species 0.000 description 2
- 241000238424 Crustacea Species 0.000 description 2
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 2
- GUBGYTABKSRVRQ-QKKXKWKRSA-N Lactose Natural products OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)C(O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O GUBGYTABKSRVRQ-QKKXKWKRSA-N 0.000 description 2
- OVRNDRQMDRJTHS-UHFFFAOYSA-N N-acelyl-D-glucosamine Natural products CC(=O)NC1C(O)OC(CO)C(O)C1O OVRNDRQMDRJTHS-UHFFFAOYSA-N 0.000 description 2
- MBLBDJOUHNCFQT-LXGUWJNJSA-N N-acetylglucosamine Natural products CC(=O)N[C@@H](C=O)[C@@H](O)[C@H](O)[C@H](O)CO MBLBDJOUHNCFQT-LXGUWJNJSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000006071 cream Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003974 emollient agent Substances 0.000 description 2
- 239000008101 lactose Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000600 sorbitol Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- 230000029663 wound healing Effects 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- 241000238143 Cancridae Species 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 241001529572 Chaceon affinis Species 0.000 description 1
- 102000008186 Collagen Human genes 0.000 description 1
- 108010035532 Collagen Proteins 0.000 description 1
- 206010012735 Diarrhoea Diseases 0.000 description 1
- 241000239366 Euphausiacea Species 0.000 description 1
- 241001235206 Farfantepenaeus brasiliensis Species 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- 241000287828 Gallus gallus Species 0.000 description 1
- 229920002683 Glycosaminoglycan Polymers 0.000 description 1
- 241000238631 Hexapoda Species 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229920000168 Microcrystalline cellulose Polymers 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229920001213 Polysorbate 20 Polymers 0.000 description 1
- 229920001214 Polysorbate 60 Polymers 0.000 description 1
- 241000238371 Sepiidae Species 0.000 description 1
- NWGKJDSIEKMTRX-AAZCQSIUSA-N Sorbitan monooleate Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O NWGKJDSIEKMTRX-AAZCQSIUSA-N 0.000 description 1
- 239000005862 Whey Substances 0.000 description 1
- 102000007544 Whey Proteins Human genes 0.000 description 1
- 108010046377 Whey Proteins Proteins 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000002479 acid--base titration Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229920001222 biopolymer Polymers 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000037396 body weight Effects 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 238000009924 canning Methods 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 210000000845 cartilage Anatomy 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 235000010980 cellulose Nutrition 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920001436 collagen Polymers 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000003544 deproteinization Effects 0.000 description 1
- 235000005911 diet Nutrition 0.000 description 1
- 230000037213 diet Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000002036 drum drying Methods 0.000 description 1
- 235000021463 dry cake Nutrition 0.000 description 1
- 238000009837 dry grinding Methods 0.000 description 1
- BEFDCLMNVWHSGT-UHFFFAOYSA-N ethenylcyclopentane Chemical compound C=CC1CCCC1 BEFDCLMNVWHSGT-UHFFFAOYSA-N 0.000 description 1
- 210000003746 feather Anatomy 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 229940069016 go-dry Drugs 0.000 description 1
- YPJJABHAGGFGAM-UHFFFAOYSA-M lithium;n,n-dimethylacetamide;chloride Chemical compound [Li+].[Cl-].CN(C)C(C)=O YPJJABHAGGFGAM-UHFFFAOYSA-M 0.000 description 1
- 241000238565 lobster Species 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 235000019813 microcrystalline cellulose Nutrition 0.000 description 1
- 239000008108 microcrystalline cellulose Substances 0.000 description 1
- 229940016286 microcrystalline cellulose Drugs 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 239000000256 polyoxyethylene sorbitan monolaurate Substances 0.000 description 1
- 235000010486 polyoxyethylene sorbitan monolaurate Nutrition 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 230000002335 preservative effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 235000014102 seafood Nutrition 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000002195 soluble material Substances 0.000 description 1
- 239000004334 sorbic acid Substances 0.000 description 1
- 229940075582 sorbic acid Drugs 0.000 description 1
- 235000010199 sorbic acid Nutrition 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 230000000699 topical effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
- C08B37/0027—2-Acetamido-2-deoxy-beta-glucans; Derivatives thereof
- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
Definitions
- This invention relates to chitin in the microcrystalline form.
- Chitin is an aminocellulose derivative that occurs widely in nature, for example, in the cell walls of fungi, bovine cartilage, cuttlefish bone and the hard shells of insects and crustaceans. Waste from the shrimp, lobster, and crab seafood industries contain 10-30% chitin and are potentially important sources of chitin. It is a mucopolysaccharide, believed to be poly-N-acetyl-D-glucosamine, with an empirical formula (C 8 H 13 O 5 N) n in which n may be any number from about 100 into the thousands range.
- Microcrystalline cellulose, collagen and chitin are known in dispersion form and are useful as stabilizers in aqueous food systems which must resist the effects of repeated freeze-thaw and retort canning cyles.
- U.S. Pat. No. 3,847,897 describes a method for preparing partially hydrolyzed chitin and shearing it into a microcrystalline suspension. In the process of U.S. Pat. No. 3,847,897, as evidenced in Table I thereof, there is a drastic drop in viscosity and thus the very large amount of molecular degradation apparently occurring in the first 5 mins. of hydrolysis in aqueous HCl.
- Natural chitin has a levo (-) optical rotation, believed to be beneficial in certain uses. Especially for biological and physiological purposes, such as topical wound-healing treatments, it is recognized that the native--i.e., natural--conformation of a biopolymer usually is required (U.S. Pat. No. 3,632,754). Hence, there was a need for a method of preparing microcrystalline chitin which would not be harsh enough to alter the molecular conformation.
- microcrystalline, dispersible chitin powder can be made, especially of a predetermined molecular weight and natural molecular conformation.
- microcrystalline chitin It is an object of this invention to provide an improved microcrystalline chitin. It is a further object to provide microcrystalline chitin in powder form. It is still a further object to provide friable, dispersible microcrystalline chitin powder. It is a further object to provide microcrystalline chitin of reduced molecular weight but of natural molecular conformation. Another object is to provide microcrystalline chitin of predetermined molecular weight by a reliable, reproducible process.
- a friable dispersible microcrystalline chitin powder having natural molecular conformation and reduced molecular weight of any desired level, can be made by the following process.
- Particulated chitin is dispersed in a mixture of phosphoric acid and a lower aliphatic alcohol, preferably containing less than 50% by volume phosphoric acid, and heated to hydrolyze the chitin to the desired lower molecular weight.
- the hydrolyzed chitin is then separated from the liquid and washed several times with water to remove residual acid and alcohol and thereafter redispersed in 5 to 25% water where it is subjected to high speed shear forces.
- the water was removed from the dispersion by drying said sheared hydrolyzed chitin followed by grinding said dry chitin to the desired size.
- the hydrolyzing step is preferably carried out by heating a mixture of phosphoric acid and 2-propanol at a boiling temperature for 1/2 to 11/2 hrs. Prolonged boiling causes the chitin to caramelize and hence boiling over 2 hours is undesirable. After the boiling step, the soluble material is discarded and the hydrolyzed chitin physically reduced to a nearly dry condition before proceeding to the shearing step.
- the substantially dry hydrolyzed chitin is dispersed in water by adding about 5 to 25% water and subjecting the mixture high speed shear forces such as obtained in a Waring Blendor at about 20,500 RPM. A uniform dispersion is usually obtained in 15 to 20 minutes.
- the shearing step is carried out at ambient temperature. Any phosphoric acid may be neutralized if desired and the sheared chitin can be washed essentially salt free before drying and grinding to a powder.
- Freeze drying is preferred but other low temperature drying methods are suitable. Drum drying at low temperature or spray drying in a vacuum may also be used. The principal aspect of the drying step is to prevent formation of a horny, non-friable material.
- Any dry grinding process may be used such as an impact mill, e.g., Wiley Mill, ball mill or roller mill. Grinding may be carried out until all particles pass a 10 mesh or finer U.S. Standard sieve. For many uses, it is preferred that the particles have a size of 250 microns or less, e.g., such that they pass through a 60 mesh U.S. Standard sieve.
- a product is obtained that is particles of chitin characterized as agglomerates of needle-like microcrystals, as seen under a 600 power microscope. These particles are capable of being dispersed in water to form a stable dispersion by mere hand stirring.
- the treatment can be repeated, using a fresh bath of H 3 PO 4 and 2-propanol. Both boiling and shearing contribute to chain shortening, so that it is possible to obtain the desired molecular weight by varying the severity of either or both steps. Three treatments with the hydrolyzing medium and shearing steps usually are required to reduce the molecular weight into the 5,000-10,000 range.
- the preferred acid is 85% H 3 PO 4 and the preferred hydrolyzing medium is about 33% by vol. H 3 PO 4 (85%) and about 67% by vol. of 2-propanol.
- Larger proportions of 85% H 3 PO 4 are operable, but their use reduces the molecular weight of chitin more rapidly, so that control of the process is less easily accomplished. Such mixtures also dissolve more of the chitin than desired, thus reducing the yield of microcrystalline powder.
- Ethanol and 1-propanol can be used instead of 2-propanol, but with less satisfactory results.
- microcrystalline chitin is further characterized in having phosphorus content in the polymeric molecule; however, such content usually is less than 1%.
- the phosphorus is present as a phosphate in the polymer molecule.
- a conventional preservative such as sorbic acid can be incorporated with the powder, if desired, to prevent mold-formation.
- any of a variety of well-known dispersing agents such as carboxymethyl cellulose and various sorbitol derivatives can be added to the powder.
- Chitin from various sources such as red, blue, rock and king crabs, krill, lobsters, shrimp and other crustaceans can be used.
- sources such as red, blue, rock and king crabs, krill, lobsters, shrimp and other crustaceans
- response to the process of this invention varies somewhat. It is quite easy, nevertheless, to compensate for these variations and obtain the desired results.
- Chitin prepared under mild conditions of decalcification and deproteinization and having a natural levo (-) optical rotation are preferred as starting materials.
- some commercial chitins have a dextro (+) optical rotation because of the severity of their method of preparation.
- Such chitins yield microcrystalline chitins having a dextro (+) optical rotation.
- Microcrystalline chitin of low molecular weight prepared by prolonged or multi-stage treatments of naturally levo chitin by the process of this invention may also be dextrorotatory. In either case these chitins may be converted to products having the natural levo (-) optical rotation by allowing the material to stand in a dimethylacetamide-lithium chloride solution for a period of time.
- a procedure for acetyl determination by hydrolysis as a measure of chemical integrity of the products was based on the hydrolysis of the acetyl groups by strong alkali, and the conversion of them to acetic acid.
- the acetic acid was distilled off as an azeotrope with water.
- the amount of acetic acid was determined by an acid-base titration.
- the sample of chitin (approximately 0.01 g) was placed in a round bottom flask with 40 ml of 50% NaOH. The mixture was refluxed for 1.5 hours and was allowed to cool before being placed in an ice bath. After 0.5 hour in the ice bath, 25 ml of H 3 PO 4 (conc. 85%) was added slowly to the flask.
- the mixture was then fractionally distilled using a Vigreux column. As the distilling flask began to go dry, 15 ml of hot distilled water was added to the flask. This step was repeated until 250 ml of distillate was collected to insure that distillation of the acetic acid was complete.
- the slurry was then centrifuged at 2000 RPM. After removal of the supernatant liquid, the chitin was washed twice with hot water and then once with acetone. After each wash, the slurry was centrifuged again and the supernatant liquid removed.
- the chitin mixture thus obtained was filtered under suction to reduce the liquid content as much as possible, and then the damp solid was sheared for 15 minutes with about 10% its weight of water. Shearing was done in a Waring Blendor at 20,500 RPM, starting with the mixture at room temperature and allowing the temperature to rise from the heat generated by the shearing action. The resulting dispersion was spread evenly on trays and freeze-dried.
- the dry cake of microcrystalline chitin was broken up and subjected to dry shearing at about 5000 RPM for about 2 minutes to create a particulate that could be fed into a laboratory Wiley mill.
- the chitin particulate was then ground in a Wiley laboratory mill until it passed through a 40 mesh U.S. Standard sieve.
- the yield of white, microcrystalline chitin powder was 130 g. Its phosphorus content was about 0.4% and its molecular weight (wt. average) was about 75,000. It had an optical rotation of about -80°.
- Example 1 The procedure of Example 1 was iterated using the product of Example 1 as the starting material. A white microcrystalline chitin was obtained that had a molecular weight (wt. average) of about 33,600 and an optical rotation of about -10°.
- Example 1 The procedure of Example 1 was iterated using the product of Example 2 as the starting material. A white microcrystalline chitin was obtained that had a molecular weight (wt. average) of about 5,600 and an optical rotation of about +71°.
- Example 1 The procedure of Example 1 was repeated, using a 1:1 vol. ratio of 85% H 3 PO 4 and 2-propanol. After only one boiling step and one shearing step, followed by neutralization with aqueous NaOH to pH 7.0, and drying, the molecular weight was found to be about 10,500, the acetyl value 19.7 and the phosphorus content 5.30%.
- the specific rotation of the soluble fraction of this material initially was (+) 50° and after standing for one week in dimethylacetamide -5% LiCl its specific rotation reverted to (-)25°.
- the powder of this invention is strikingly effective as a supplement to lactose-rich chicken diets, producing impressive gains in body weight and reductions in the diarrhea and scruffy feathers normally caused by lactose-rich whey feed (see Example IV of U.S. Ser. No. 051,850 filed June 25, 1979, by Austin, Zikakis and Brine).
- Example 1 The procedure of Example 1 was repeated using a chitin derived from the blue crab (initial molecular weight about 1 ⁇ 10 6 ). Employing 33% by vol. H 3 PO 4 (85%) and about 67% by vol. 2-propanol, after only one boiling step and one shearing step the molecular weight was found to be about 84,500. Phosphorus content was 0.39%. The product had an optical rotation of about 0°.
- Examples 1, 2 and 3 illustrate how the molecular weight of the microcrystalline chitin powder can be controlled. It is, of course, obvious that one need not go through the freeze dry and grinding to powder steps but one time, namely, as the final steps of making the chitin powder.
- the molecular weight of the final product can be controlled by repeating or varying the steps of phosphoric acid and alcohol treatment and the shearing of the damp solid resulting from said treatment.
- the microcrystalline chitin powder of this invention fills a need in the art. It is more convenient and economical to store and ship than the microcrystalline chitin dispersion of the prior art, and can be dispersed readily if desired.
- the process of this invention provides a reliable method for preparing this powder in any desired molecular weight in a range from about 450,000 down to about 5,000. Surprisingly, this can be accomplished without adverse effect on the chemical integrity of the polymer.
Abstract
A friable, dispersible microcrystalline chitin powder and a process of making same by treating particulate chitin at an elevated temperature with phosphoric acid, particularly with phosphoric acid diluted with a lower aliphatic alcohol, separating the treated chitin and subjecting same to shearing in an inert liquid medium until a uniform dispersion is obtained, thereafter separating the sheared chitin and drying and grinding same to a fine powder.
Description
The Government of the United States has rights in this invention pursuant to Grant No. 04-7-158-44120 from the U.S. Department of Commerce.
This invention relates to chitin in the microcrystalline form.
Chitin is an aminocellulose derivative that occurs widely in nature, for example, in the cell walls of fungi, bovine cartilage, cuttlefish bone and the hard shells of insects and crustaceans. Waste from the shrimp, lobster, and crab seafood industries contain 10-30% chitin and are potentially important sources of chitin. It is a mucopolysaccharide, believed to be poly-N-acetyl-D-glucosamine, with an empirical formula (C8 H13 O5 N)n in which n may be any number from about 100 into the thousands range.
Microcrystalline cellulose, collagen and chitin are known in dispersion form and are useful as stabilizers in aqueous food systems which must resist the effects of repeated freeze-thaw and retort canning cyles. U.S. Pat. No. 3,847,897 describes a method for preparing partially hydrolyzed chitin and shearing it into a microcrystalline suspension. In the process of U.S. Pat. No. 3,847,897, as evidenced in Table I thereof, there is a drastic drop in viscosity and thus the very large amount of molecular degradation apparently occurring in the first 5 mins. of hydrolysis in aqueous HCl.
U.S. Pat. No. 4,063,016 (Example VII) describes stirring chitin with a 50:50 (by vol.) mixture of phosphoric acid and 2-propanol at room temperature, as one step in the preparation of a phosphate salt of chitin. Most of the chitin was soluble in that system. Hydrolysis was not mentioned, and apparently was prevented by the low temperature of the treatment.
Natural chitin has a levo (-) optical rotation, believed to be beneficial in certain uses. Especially for biological and physiological purposes, such as topical wound-healing treatments, it is recognized that the native--i.e., natural--conformation of a biopolymer usually is required (U.S. Pat. No. 3,632,754). Hence, there was a need for a method of preparing microcrystalline chitin which would not be harsh enough to alter the molecular conformation.
In summary, the prior art has not taught that microcrystalline, dispersible chitin powder can be made, especially of a predetermined molecular weight and natural molecular conformation.
It is an object of this invention to provide an improved microcrystalline chitin. It is a further object to provide microcrystalline chitin in powder form. It is still a further object to provide friable, dispersible microcrystalline chitin powder. It is a further object to provide microcrystalline chitin of reduced molecular weight but of natural molecular conformation. Another object is to provide microcrystalline chitin of predetermined molecular weight by a reliable, reproducible process.
It has been found that a friable dispersible microcrystalline chitin powder, having natural molecular conformation and reduced molecular weight of any desired level, can be made by the following process. Particulated chitin is dispersed in a mixture of phosphoric acid and a lower aliphatic alcohol, preferably containing less than 50% by volume phosphoric acid, and heated to hydrolyze the chitin to the desired lower molecular weight. The hydrolyzed chitin is then separated from the liquid and washed several times with water to remove residual acid and alcohol and thereafter redispersed in 5 to 25% water where it is subjected to high speed shear forces. The water was removed from the dispersion by drying said sheared hydrolyzed chitin followed by grinding said dry chitin to the desired size.
The hydrolyzing step is preferably carried out by heating a mixture of phosphoric acid and 2-propanol at a boiling temperature for 1/2 to 11/2 hrs. Prolonged boiling causes the chitin to caramelize and hence boiling over 2 hours is undesirable. After the boiling step, the soluble material is discarded and the hydrolyzed chitin physically reduced to a nearly dry condition before proceeding to the shearing step.
After removal of substantially all of the hydrolyzing solution, the substantially dry hydrolyzed chitin is dispersed in water by adding about 5 to 25% water and subjecting the mixture high speed shear forces such as obtained in a Waring Blendor at about 20,500 RPM. A uniform dispersion is usually obtained in 15 to 20 minutes. The shearing step is carried out at ambient temperature. Any phosphoric acid may be neutralized if desired and the sheared chitin can be washed essentially salt free before drying and grinding to a powder.
Freeze drying is preferred but other low temperature drying methods are suitable. Drum drying at low temperature or spray drying in a vacuum may also be used. The principal aspect of the drying step is to prevent formation of a horny, non-friable material.
Any dry grinding process may be used such as an impact mill, e.g., Wiley Mill, ball mill or roller mill. Grinding may be carried out until all particles pass a 10 mesh or finer U.S. Standard sieve. For many uses, it is preferred that the particles have a size of 250 microns or less, e.g., such that they pass through a 60 mesh U.S. Standard sieve. By this method a product is obtained that is particles of chitin characterized as agglomerates of needle-like microcrystals, as seen under a 600 power microscope. These particles are capable of being dispersed in water to form a stable dispersion by mere hand stirring.
If the molecular weight--i.e., average chain length--has not been reduced sufficiently by one boil and one shearing step, the treatment can be repeated, using a fresh bath of H3 PO4 and 2-propanol. Both boiling and shearing contribute to chain shortening, so that it is possible to obtain the desired molecular weight by varying the severity of either or both steps. Three treatments with the hydrolyzing medium and shearing steps usually are required to reduce the molecular weight into the 5,000-10,000 range.
The preferred acid is 85% H3 PO4 and the preferred hydrolyzing medium is about 33% by vol. H3 PO4 (85%) and about 67% by vol. of 2-propanol. Larger proportions of 85% H3 PO4 are operable, but their use reduces the molecular weight of chitin more rapidly, so that control of the process is less easily accomplished. Such mixtures also dissolve more of the chitin than desired, thus reducing the yield of microcrystalline powder. Ethanol and 1-propanol can be used instead of 2-propanol, but with less satisfactory results.
The microcrystalline chitin is further characterized in having phosphorus content in the polymeric molecule; however, such content usually is less than 1%. The phosphorus is present as a phosphate in the polymer molecule.
A conventional preservative such as sorbic acid can be incorporated with the powder, if desired, to prevent mold-formation. Also, if desired, any of a variety of well-known dispersing agents such as carboxymethyl cellulose and various sorbitol derivatives can be added to the powder.
Chitin from various sources, such as red, blue, rock and king crabs, krill, lobsters, shrimp and other crustaceans can be used. Depending on the sources and on the purity of the chitin, response to the process of this invention varies somewhat. It is quite easy, nevertheless, to compensate for these variations and obtain the desired results.
Chitin prepared under mild conditions of decalcification and deproteinization and having a natural levo (-) optical rotation are preferred as starting materials. However, some commercial chitins have a dextro (+) optical rotation because of the severity of their method of preparation. Such chitins yield microcrystalline chitins having a dextro (+) optical rotation. Microcrystalline chitin of low molecular weight prepared by prolonged or multi-stage treatments of naturally levo chitin by the process of this invention may also be dextrorotatory. In either case these chitins may be converted to products having the natural levo (-) optical rotation by allowing the material to stand in a dimethylacetamide-lithium chloride solution for a period of time.
Molecular weight was calculated from intrinsic viscosity by the modified Staudinger equation: [α]kMvol a, in which [α]=intrinisic viscosity, Mvol ≃Mw =weight average molecular weight and K and α are constants (8.93×10-4 and 0.71, respectively. Intrinsic viscosity was determined using a Cannon-Fenske Viscometer (size 100) giving a solvent efflux time greater than 100 seconds. The temperature was maintained at 30.0° C. (±0.02°) by a constant temperature bath. N,N-dimethylacetamide (DMAc)--5% LiCl was used as the solvent.
Optical activity was determined as follows: The observed rotation, θ, of the chitin solutions was measured in N,N-dimethylacetamide (DMAc)--5% LiCl using a Polyscience Polarimeter Model SR6. The solutions were filtered through glass fiber filters before the rotations were observed. The rotations were measured to the nearest 0.1% and at two concentrations. The specific rotations were calculated by the following equation: [α]D T =θ/lc, where c--concentration in g/ml; l--cell length in decimeters; D--wavelength of light (D line of sodium lamp); T--temperature, 25° C.
A procedure for acetyl determination by hydrolysis as a measure of chemical integrity of the products was based on the hydrolysis of the acetyl groups by strong alkali, and the conversion of them to acetic acid. The acetic acid was distilled off as an azeotrope with water. The amount of acetic acid was determined by an acid-base titration.
The sample of chitin (approximately 0.01 g) was placed in a round bottom flask with 40 ml of 50% NaOH. The mixture was refluxed for 1.5 hours and was allowed to cool before being placed in an ice bath. After 0.5 hour in the ice bath, 25 ml of H3 PO4 (conc. 85%) was added slowly to the flask.
The mixture was then fractionally distilled using a Vigreux column. As the distilling flask began to go dry, 15 ml of hot distilled water was added to the flask. This step was repeated until 250 ml of distillate was collected to insure that distillation of the acetic acid was complete.
Several aliquots (25 ml) of the distillate were titrated with 0.01 N NaOH using phenolphthalein as an indicator. The volume of titrant used for the aliquots was extrapolated to the total volume of the distillate collected.
The distillate was collected until the aliquots of the sample and a blank were equal. Finely divided filter paper (cellulose) was used as a blank. N-acetyl-glucosamine (NAG) was used as a standard and gave a value of 20.4 (21.2 calcd. for pure chitin). The percent acetyl of chitin was determined by the following equation (Lee, 1974),
The following examples illustrate the best modes contemplated for carrying out the process of this invention.
A slurry of 150 g of chitin from brown shrimp (molecular weight about 800,000) in 475 ml of 85% H3 PO4 and 1000 ml of 2-propanol was stirred mechanically while being heated gradually to boiling and held there for about 11/2 hrs. It was then quenched with tap water (2.5 l.) and allowed to stand at room temperature for 15 mins.
The slurry was then centrifuged at 2000 RPM. After removal of the supernatant liquid, the chitin was washed twice with hot water and then once with acetone. After each wash, the slurry was centrifuged again and the supernatant liquid removed.
The chitin mixture thus obtained was filtered under suction to reduce the liquid content as much as possible, and then the damp solid was sheared for 15 minutes with about 10% its weight of water. Shearing was done in a Waring Blendor at 20,500 RPM, starting with the mixture at room temperature and allowing the temperature to rise from the heat generated by the shearing action. The resulting dispersion was spread evenly on trays and freeze-dried.
The dry cake of microcrystalline chitin was broken up and subjected to dry shearing at about 5000 RPM for about 2 minutes to create a particulate that could be fed into a laboratory Wiley mill. The chitin particulate was then ground in a Wiley laboratory mill until it passed through a 40 mesh U.S. Standard sieve.
The yield of white, microcrystalline chitin powder was 130 g. Its phosphorus content was about 0.4% and its molecular weight (wt. average) was about 75,000. It had an optical rotation of about -80°.
The procedure of Example 1 was iterated using the product of Example 1 as the starting material. A white microcrystalline chitin was obtained that had a molecular weight (wt. average) of about 33,600 and an optical rotation of about -10°.
The procedure of Example 1 was iterated using the product of Example 2 as the starting material. A white microcrystalline chitin was obtained that had a molecular weight (wt. average) of about 5,600 and an optical rotation of about +71°.
The procedure of Example 1 was repeated, using a 1:1 vol. ratio of 85% H3 PO4 and 2-propanol. After only one boiling step and one shearing step, followed by neutralization with aqueous NaOH to pH 7.0, and drying, the molecular weight was found to be about 10,500, the acetyl value 19.7 and the phosphorus content 5.30%. The specific rotation of the soluble fraction of this material initially was (+) 50° and after standing for one week in dimethylacetamide -5% LiCl its specific rotation reverted to (-)25°.
Smooth, emollient creams based on commercial sorbitol products "Span 80," "Tween 20" and "Tween 60" were made from the water-sheared dispersion of Example 1 (before drying) by mixing two parts of the chitin dispersion with one part by weight of each sorbitol agent. The resulting emollient creams were physically stable and completely free from mold on standing several months at room temperature, in contrast to the 10% chitin dispersion itself, which developed a layer of mold within about one week when exposed to the air.
The powder of this invention is strikingly effective as a supplement to lactose-rich chicken diets, producing impressive gains in body weight and reductions in the diarrhea and scruffy feathers normally caused by lactose-rich whey feed (see Example IV of U.S. Ser. No. 051,850 filed June 25, 1979, by Austin, Zikakis and Brine).
The procedure of Example 1 was repeated using a chitin derived from the blue crab (initial molecular weight about 1×106). Employing 33% by vol. H3 PO4 (85%) and about 67% by vol. 2-propanol, after only one boiling step and one shearing step the molecular weight was found to be about 84,500. Phosphorus content was 0.39%. The product had an optical rotation of about 0°.
Examples 1, 2 and 3 illustrate how the molecular weight of the microcrystalline chitin powder can be controlled. It is, of course, obvious that one need not go through the freeze dry and grinding to powder steps but one time, namely, as the final steps of making the chitin powder. The molecular weight of the final product can be controlled by repeating or varying the steps of phosphoric acid and alcohol treatment and the shearing of the damp solid resulting from said treatment.
Substantial improvements in both acceleration and quality of wound-healing have been demonstrated by applying water-dispersions of the powder of this invention to severe abrasions, cuts and cracks caused by chapping.
Thus, the microcrystalline chitin powder of this invention fills a need in the art. It is more convenient and economical to store and ship than the microcrystalline chitin dispersion of the prior art, and can be dispersed readily if desired. The process of this invention provides a reliable method for preparing this powder in any desired molecular weight in a range from about 450,000 down to about 5,000. Surprisingly, this can be accomplished without adverse effect on the chemical integrity of the polymer.
While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made herein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.
Claims (6)
1. A process of making a dispersible chitin powder which comprises the sequential steps of
(a) dispersing a particulate chitin in a mixture of phosphoric acid and a lower aliphatic alcohol,
(b) heating said dispersion to hydrolyze the chitin to the desired lower molecular weight,
(c) removing the hydrolyzed chitin from the dispersion,
(d) redispersing the hydrolyzed chitin in water by mixing same with 5 to 25% water and subjecting the mixture to high speed shear forces,
(e) removing the water from the dispersion by drying said sheared hydrolyzed chitin,
(f) grinding the dried sheared hydrolyzed chitin to the desired particle size.
2. The process of claim 1 in which the phosphoric acid in step (a) is present in an amount less than 50% by volume in the mixture of phosphoric acid and lower aliphatic alcohol.
3. The process of claim 1 in which the lower aliphatic alcohol is 2-propanol.
4. The process of claim 2 in which the mixture of phosphoric acid and lower aliphatic alcohol consists of 33 Vol. % of 85% H3 PO4 and 67 Vol. % of 2-propanol.
5. The process of claim 1 which the drying process of step (e) is freeze drying.
6. The process of claim 4 in which the dispersion is phosphoric acid and 2-propanol is heated at boiling for 1/2 hr. to 11/2 hrs.
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US4931551A (en) * | 1988-07-05 | 1990-06-05 | University Of Delaware | Dispersions of chitin and product therefrom |
US4958011A (en) * | 1983-06-27 | 1990-09-18 | Bade Maria L | Ester-stabilized chitin |
WO1994006484A1 (en) * | 1992-09-14 | 1994-03-31 | Novasso Oy | Wound protecting dressing |
US5705634A (en) * | 1995-03-02 | 1998-01-06 | Perimmune Holdings, Inc. | High yield preparation of dimeric to decameric chitin oligomers |
US5830883A (en) * | 1995-11-06 | 1998-11-03 | Duquesne University Of The Holy Ghost | Methods of creating a unique chitosan and employing the same to form complexes with drugs, delivery of the same within a patient and a related dosage form |
US6193988B1 (en) | 1994-01-13 | 2001-02-27 | Stoner, Ii Richard J. | Tuber planting system comprising chitin or chitosan |
US6663942B1 (en) | 1995-05-18 | 2003-12-16 | Fort James Corporation | Crosslinkable creping adhesive formulations applied to a dryer surface or to a cellulosic fiber |
US6689250B1 (en) | 1995-05-18 | 2004-02-10 | Fort James Corporation | Crosslinkable creping adhesive formulations |
US7892414B1 (en) | 2004-11-19 | 2011-02-22 | The United States Of America As Represented By The Secretary Of Army | Electrochemical biosensors, applications and methods of making biosensors |
CN106432540A (en) * | 2016-09-13 | 2017-02-22 | 浙江大学 | Chitin micro-powder preparation method |
US20170173403A1 (en) * | 2011-03-24 | 2017-06-22 | University Of Maine System Board Of Trustees | Biodegradable Materials and Methods of Making the Same |
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Publication number | Priority date | Publication date | Assignee | Title |
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US4958011A (en) * | 1983-06-27 | 1990-09-18 | Bade Maria L | Ester-stabilized chitin |
US4931551A (en) * | 1988-07-05 | 1990-06-05 | University Of Delaware | Dispersions of chitin and product therefrom |
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US6193988B1 (en) | 1994-01-13 | 2001-02-27 | Stoner, Ii Richard J. | Tuber planting system comprising chitin or chitosan |
US5705634A (en) * | 1995-03-02 | 1998-01-06 | Perimmune Holdings, Inc. | High yield preparation of dimeric to decameric chitin oligomers |
US6812281B2 (en) | 1995-05-18 | 2004-11-02 | Fort James Corporation | Crosslinkable creping adhesive formulations |
US6815497B1 (en) | 1995-05-18 | 2004-11-09 | Fort James Corporation | Crosslinkable creping adhesive formulations |
US6663942B1 (en) | 1995-05-18 | 2003-12-16 | Fort James Corporation | Crosslinkable creping adhesive formulations applied to a dryer surface or to a cellulosic fiber |
US6689250B1 (en) | 1995-05-18 | 2004-02-10 | Fort James Corporation | Crosslinkable creping adhesive formulations |
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US5830883A (en) * | 1995-11-06 | 1998-11-03 | Duquesne University Of The Holy Ghost | Methods of creating a unique chitosan and employing the same to form complexes with drugs, delivery of the same within a patient and a related dosage form |
US5900408A (en) * | 1995-11-06 | 1999-05-04 | Duquesne University Of The Holy Ghost | Methods of creating a unique chitosan and employing the same to form complexes with drugs, delivery of the same within a patient and a related dosage form |
US7892414B1 (en) | 2004-11-19 | 2011-02-22 | The United States Of America As Represented By The Secretary Of Army | Electrochemical biosensors, applications and methods of making biosensors |
US20170173403A1 (en) * | 2011-03-24 | 2017-06-22 | University Of Maine System Board Of Trustees | Biodegradable Materials and Methods of Making the Same |
US10065080B2 (en) * | 2011-03-24 | 2018-09-04 | University Of Maine System Board Of Trustees | Biodegradable materials and methods of making the same |
CN106432540A (en) * | 2016-09-13 | 2017-02-22 | 浙江大学 | Chitin micro-powder preparation method |
CN106432540B (en) * | 2016-09-13 | 2019-05-14 | 浙江大学 | A kind of preparation method of chitin micro mist |
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